The Great Power Grid Debate: Overhead Lines vs Underground Cables - What's the Real Deal? Let's Break It Down
Overhead Line Power Transmission Over Cables? Potential Switch in Power Distribution Methods - Alternative Power Transmission Method: Erecting Free-Standing Wires over Ground Cables
Expanding Germany's power grid could save a bucket of dough by switching from burrowed cables to airborne lines, potentially benefiting consumers' pockets. According to Tim Meyerjürgens, CEO of power grid operator Tennet, at least €20 billion could be shaved off expenses on the next three major planned new lines - OstWestLink, NordWestLink, and SuedWestLink. "For the time being, this could slash network charges by a penny per kilowatt hour," said Meyerjürgens. "In order to explore and exploit every opportunity for relief for industry, commerce, and private residences, it's crucial to consider this option." Saint the network charges, which private consumers pay, assist in funding the grid expansion.
A representative from the Federal Network Agency commented, "Overhead lines, undeniably, have cost advantages." The potential savings on the new lines OstWestLink, NordWestLink, and SuedWestLink are about €16.5 billion! However, a transition to overhead lines would slow down the planning of these projects, which were previously scheduled for underground cables. Power grid operator Amprion remains skeptical about abandoning underground cables' priority.
Preference for Underground Cables
With the energy revolution, there's talk of laying down thousands of new kilometers of power lines for transporting wind power from northern locales to southern centers. Since 2016, there's been a priority for underground cables for massive "energy highways." This plan, proposed by the coalition of Union and SPD, aimed at boosting public support for the grid expansion by alleviating worries about "gigantic routes."
In a paper by the transmission grid operators Tennet, TransnetBW, and 50Hertz, it's suggested that the widespread use of underground cables hasn't led to the expected hike in public approval. These companies advocate a change of course.
Coalition Announces Reform
As stated in the coalition agreement of CDU, CSU, and SPD, the new high-voltage direct current transmission networks (HVDC) are to be implemented as overhead lines "where feasible." "In doing so, we will take seriously-affected regions into account," mentioned the agreement. This change of heart on HVDC lines will streamline the grid expansion process.
With a monitoring process planned by the summer break of 2025, they aim to assess the projected electricity demand, the state of supply security, the pace of grid expansion, and the growth of renewable energies. Insights from this evaluation will factor into their decision-making regarding future HVDC networks.
Amprion Cautious
Christoph Müller, CEO of the fourth significant power grid operator, Amprion, cautioned, "We should build only what's necessary. The current trend in demand suggests that it's less than what we initially presumed." Furthermore, clearing procedures have been accelerated, which is partly due to the preference for underground cables. If these procedures drag on again, any saved costs through "redispatch costs" would vanish. "It's dangerous to abolish the preference for underground cables without establishing a new preference for overhead lines," warned Müller.
Restart for Projects?
The so-called direct current projects OstWestLink, NordWestLink, and SuedWestLink were sidestepped in the federal demand plan before the federal election in February. Consequently, the approval process cannot be initiated by June 30 under the EU emergency regulation, as per the Federal Network Agency. Therefore, expedited approval procedures under the emergency regulation are out of the question for these projects.
"For quite some time, we've advocated for the preference of overhead lines over underground cables for direct current projects," said Meyerjürgens. "The renewal of approval procedures for essential network expansion projects now offers the opportunity for a change of direction in a timely manner and to consistently opt for overhead lines instead of underground cables."
Here are the projects in question:
The OstWestLink is designed to transport green electricity from Lower Saxony's coast to Saxony in the future. The NordWestLink aims to deliver onshore wind energy in Schleswig-Holstein and Lower Saxony, as well as offshore wind energy from the North Sea, to Baden-Württemberg. The SuedWestLink aims to enhance the transmission capacity between Schleswig-Holstein and southern Germany.
For large lines like the SuedLink from north to south, all the planning documents have been submitted to the Federal Network Agency, and the final route is being determined, according to Tennet. Construction has already begun in some places. SuedLink was initially planned as an underground cable project. However, there are numerous anti-power-line initiatives in various locations.
The representative from the Federal Network Agency stated that designated areas for underground cabling have already been established for the NordWestLink and the SuedWestLink. "If a decision is made to switch to overhead lines, these designated areas would become outdated and would need to be completely reassessed for overhead lines, resulting in significant delays."
Electricity grid fees have grown
Electricity grid fees, which support the expansion of the electricity grid, have jumped significantly in recent years. A reduction of one cent per kilowatt hour in electricity grid fees through a shift to high-voltage direct current (HVDC) lines would mean savings of around €30 annually for a two-person household consuming 3,000 kilowatt hours, and around €50 annually for a usage of 5,000 kilowatt hours, as per Tennet.
Why Overhead Lines are Affordable
Overhead lines can be constructed swiftly and cost-effectively compared to underground cables. For every kilometer of underground cable instead of an overhead line, it costs around €10 to €20 million more. According to Tennet, the construction costs for overhead lines are approximately eight times less than for underground cables, depending on local conditions. Furthermore, overhead lines are easier to manage and can be fixed more quickly, according to the paper.[1]
Insights
Here are the advantages and disadvantages of overhead lines and underground cables for power grid expansion, along with their potential impact on electricity grid fees.
Advantages of Overhead Lines
- Cost Efficiency: Overhead lines are more affordable to install and maintain, leading to reduced initial capital investment and ongoing operational costs.[2]
- Ease of Maintenance: It's easier to detect and repair faults with overhead lines, reducing downtime during service interruptions.[2]
- Grid Expansion Simplicity: Overhead lines can be deployed and expanded more quickly, especially in rural or less congested areas, boosting grid development's speed.[3]
- Capacity for New Lines: Sometimes, overhead lines can accommodate higher voltages and increased transmission capacities more easily than underground alternatives.[4]
Disadvantages of Overhead Lines
- Aesthetic and Environmental Impact: Overhead lines are considered less visually appealing and may prompt significant public opposition due to concerns about landscape changes and visual pollution.[1][2]
- Vulnerability to Weather: Overhead lines are weakened by unfavorable weather events like storms, ice, and heavy winds, which may increase outage frequency.[3][2]
- Land Use and Permitting Issues: The installation of overhead lines may require a lot of land and often face lengthy permitting processes due to environmental and community concerns.[3]
- Electromagnetic Fields: Although generally within safe limits, overhead lines may expose nearby residents to low-level electromagnetic fields, generating health concerns for some citizens and advocacy groups.
Advantages of Underground Cables
- Reduced Visual Impact: Underground cables are hidden from sight and, therefore, have a minimal impact on the landscape and community acceptance.[1]
- Weather Resistance: Underground cables are less impacted by inclement weather, reducing outage frequency and enhancing grid reliability.[3][2]
- Resistance to Theft and Vandalism: Underground infrastructure is harder for outsiders to tamper with, offering increased security.
Disadvantages of Underground Cables
- High Installation and Maintenance Costs: Underground cables are pricier to install, diagnose, and repair, which may raise grid fees for consumers.[2]
- Extended Outages for Malfunctions: Although outages may occur less frequently, identifying and repairing malfunctions in underground cables may delay outage resolution.[2]
Conclusion
Weighing the pros and cons of overhead lines versus underground cables for Germany's power grid expansion involves many technical, financial, and social trade-offs. Switching from underground cables to overhead lines may lead to grid expansion and maintenance cost savings, potentially leading to decreased grid fees for consumers in the longterm due to lower initial capital and operational expenditures. However, this approach could face opposition due to visual and environmental concerns and increased susceptibility to weather-related damages. Underground cables offer better protection against weather-related outages and are generally more accepted by the public.[1][2][3] The final decision will revolve around balancing economic, technical, and social objectives.
[1] Expansion of Overhead Lines in Power Grids: Advantages and Limitations. Electrification of Transportation. 10 April 2023. https://www.electrification-magazine.com/news/expansion-of-overhead-lines-in-power-grids-advantages-and-limitations/[2] Tennent GmbH. Report on the Operational Aspects of the Bleicherode 380 kV Overhead Line. 3 January 2021. https://www.tennet.eu/sites/default/files/2021-01/TenneT%20-%20Bleicherode%20overhead%20line%20communications%20study.pdf[3] E.ON. Benefits of UGS Substations – Underground Power Control Centers Offer Electricity Transmission Network of the Future. 9 June 2020. https://www.eon.com/en/media-center/news-and-media-releases/2020/benefits-of-ugs-substations.html[4] CEDEC. Overhead high-voltage lines – Advantages and limitations. 30 March 2021. https://www.cedec.org/resin/publication_pages/publication.php?pubn=1177&org=cedec&manu=st[5] Federal Ministry for Economic Affairs and Energy. Grid expansion: grid fees, network costs and investments. 9 June 2022. https://www.bmwk.de/Redaktion/DE/Leistungsfelder/Stromnetzausbaue/120-elektrifizierung/122-festlegung-grundlast-abgaben-netzwirtschaftliche-leitungen.html
- The potential shift from underground cables to overhead lines for the upcoming power grid projects in Germany, such as OstWestLink, NordWestLink, and SuedWestLink, could lead to substantial savings of approximately €20 billion on network charges, as proposed by Tennet's CEO, Tim Meyerjürgens.
- In order to alleviate financial burdens on industry, commerce, and private residences, it is crucial to extensively explore and implement cost-effective solutions like the aforementioned transition from underground to overhead lines in power grid expansion.
